Re: USB Audio Class Device with custom filtering
Re: USB Audio Class Device with custom filtering
- Subject: Re: USB Audio Class Device with custom filtering
- From: Jeff Moore <email@hidden>
- Date: Thu, 15 Jan 2009 11:33:29 -0800
The USB audio class driver we ship on the system allows for plug-ins
of a sort. I can't recall how much access to the IO pathways such a
plug-in gets, but I think it was written with your usage case in mind.
Hopefully, one of the folks that work on that driver can chime in and
fill in some of the blanks on this. Otherwise, your best bet is
probably going to be going through our Developer Support folks if you
want to pursue this avenue.
On the other hand, if you want to write a custom USB driver, it sounds
like the area you are most in need of help is with writing code for
the USB controller on the system. Toward that end, there is a version
of our USB audio class driver in the Darwin code base, but I have no
idea how old it is. Even if it is pretty old, it will still provide a
good idea about programming the controllers and, possibly more
importantly, an understanding of how the controller side of the driver
integrates with audio side of the driver.
I think the IOKit examples also have some more generic examples of
programming the USB controller as well. In fact, you might want to
start with those and move on to looking at the USB audio driver once
you have a better understanding of the controller.
On Jan 15, 2009, at 7:04 AM, Luke Hollingworth wrote:
I am developing a USB headphone device for binaural filtering with
head tracking. The micro controller on the device has drivers so it
would show up as a USB Audio Device. I would though need to do
filtering on the audio in the driver on OS X based on tracking
information received from the device and so I believe I would need a
custom driver of sorts, unless anyone knows of a different approach?
I've already read the Audio Device Driver Programming Guide which is
great for answering where I could perform the filtering and how I
could implement user control but I am unsure how I would then
transmit and receive the data via the USB interface. Are there any
other sample projects available for this situation or any other
avenues of research any body could suggest?
Alternatively, if there is anybody on the list would like offer
their services in designing the driver feel free to email me.
--
Jeff Moore
Core Audio
Apple
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